his palm turning into gold is found in Tsung-is Supplement to Tien-tais Three Major Works.
8. Lotus Sutra, chap. 16. About this phrase, Nichiren Daishonin states in The
Record of the Orally Transmitted Teachings that I indicates all the people in each of the Ten Worlds, and that it means that the people of the Ten Worlds are all Buddhas eternally endowed with the three bodies.